Multicolor photographic material



July 27', 1937.

uunnconon PHOTO-[GRAPHIC MATERIAL Filed Feb. 8, 1935 -Fig, I .Light sensit lv e layer including a dyesfuff 7 Light insensitive lagerontaining undevel ped silver or clldidal silve 'Fi gZ Light sensitive layerincluding a dyestuff formiqg subsl'dnce a v Light jasnstfiv Iq er bntaimng a substance which Prevents flz formation of dygstuff mvznfog P. KNOCHE I 2,088,523

ATTORNEY Patented July 27, 1937 MULTICOLOR PHOTOGRAPHIC MATERIAL Paul Knoche. Berlin, Germany, assignor to Bela Gaspar Application February 8, 1935,.Serial No. 5,665

' In Germany February '14, 1934 7 Claims.

In the production of multi-color photographs having a plurality of colored layers poured one on to the other a creeping of the dyestuifs into adjacent layers frequently hasa very disturbing effect, in which connection remedy is sought to be obtained by precipitation of the dyestuffs in the layers.

Despite these precautions there is frequently encountered the disadvantage that the dyestuff 10 in the lowermost layer diffuses into the backing or support and colors the latter. This veil of color cannot be removed by the usual means without variation of the image situated above the same, as the means employed for destroying the dyestuif in the actual photographic or image bearing layers are unable to react with the backing or support.

Now it has been found that the small percentage of dyestuff which creeps or diffuses into the backing orsupport, intermediate or anti-halation .layers or in fact any non-image bearing layersv at all which remain uncolored in the finished image may be readily removedby incorporating therein substances which destroy the dyestuff diffusely only in these layers, either in themselves or in conjunction with the subsequent baths to which the image issubjected. .The reference to dyestuffs is also intended to include dyestuffforming substances. In this case, in addition to 3 the dyestufi-destroying agents, there may also be included chemical substances which prevent the formation of the dyestuif or act as a chemical resist.

There are a variety of ways in which the invention may be carried into effect. Thedyestuffdestroying agents are incorporated in direct fashion in the backing or support. If indifferent dyestufi-destroying agents are employed, that is to say-substances which, whilst destroying the 40 dyestuff at the desired points, will have no adverse efiect on the image during the normal time of treatment thereof, there is added to the backingor support or other layer which is to remain ultimately uncolored either a small quantity'ofcolloidal silver or an exposed silver halide emulsion. In the first case the metallic silver will undergo the same reactions as the silver in the sensitized image bearing layer or layers and destroy the dyestuff diffusely, the silver also being 5 contained difiusely in the particular layer. If

on the other hand'expose'd silver halide is employed, this requires to pass through the developing and fixing'baths in order to form metallic silver. oxidizing orcoupled reactions are also suitable for the process according to the invention.

"It is also possible to incorporate in the backing or support or intermediate or other layer the same substances as included 'inthe sensitized image bearing layer. The process according to the invention is particularly suitable for paper or films having a plurality of differently colored layers, in which the substances-according to the invention are incorporated in the backing or support..

In the accompanying drawing Fig. 1

and Fig. 2 represent sections of film.

Referring to these figures layer 1 represents a light sensitive layer which may contain a dyestuff or a dyestufi forming substance. Layer 1). represents a light insensitive layer containing a substance which prevents the formation of a dyestufi.

The light sensitive layer 11- may be the backing or support for layer a or it may be any other nonimage bearing layer. in the following examples wherein reference is made to the backing or support as the layer treated with a substance preventing the forma- It is to be understood that tionof a dyestuff that such expression includes any other non-image bearing layer into which it is desired to prevent diffusion. I

Examples 1. There is added to the backing or support, which usually consists of hardened gelatine, a

certain proportion of colloidal silver.

2. To the backing or support of a film or paper there isadded a small amount of exposed silver halide gelatin. 1:

In the developer t his silver halide gelatin will be developed and foigmin the backing or support a sufiicientquantitlof metallic silver. In the subsequent baths (5:: which the image is subjected this metalli *gsilver will undergo the same reactions as the silter in the developed image. In thedestruction f'xthe dyes'tuff, for example with an acid thiocarliamide' solution, the backing or support containing diffusely the metallic silver will destroy diffusely any dyestufi which has crept intothe same. i;

3. Thereis added to the backing or support an insoluble oxidizing agent, such as zinc chromate. In this'case the destruction of thedyestuff will take place by oxidation. I

4.-The'sensitized layers conta leuco esters, 11. e., dyestuff-forming substances, hich are con- .verted into dyestuff by oxidation. There is then incorporated in the backing or support a reducing agent, such as mercurous chloride, which will oppose the formation of the dyestuif.

The small amount of silver which is contained in the backing or support, intermediate or other layer will have no interfering effect in the observation of the image. If, as frequently the case, the final bath employed is a silver solvent, all traces of silver in the backing or support will disappear entirely.

Beyond the additions referred to it is also possible to make use of many others assuming they do not affect the sensitiveness and transparency of the sensitized layers. They should, therefore, also not creep from the backing or support, intermediate or other layer into the upper layers.

What I claim as new and desire to secure by Letters Patent is:

l. A photographic material comprising colored light sensitive layers and an uncolored light insensitive layer adjacent thereto, said uncolored layer containing a proportion of exposed silver halide, said proportion of silver halide when passed through a developing bath, yielding a quantity of metallic silver suflicient 'to assist in the destruction of any dyestuif diffusing into said uncolored layer so as to prevent the formation of-a color veil therein.

2. A photographic material comprising a light sensitive photographic layer containing a substance for coloring an image, and a light insensitive layer adjacent thereto containing an insoluble chemical substance which reacts -to destroy a compound'necessary to the formation of a color veil in said light insensitive layerl 3. A photographic material comprising a light sensitive photographic layer containing-a dyestufi forming substance convertible into a dyestuif by oxidation, and a light insensitive layer adjacent thereto containing a reducing agent for preventing oxidation of any dyestuii forming substance diffusing into said light insensitive layer to prevent the formation of a color veil in said light insensitive layer.

4. A photographic material comprising a light sensitive photographic layer containing a dyestuif, and a light insensitive layer adjacent thereto containing a chemical substance which reacts with a developing bath to produce an agent which assists in the destruction of any dyestufl diflusing into said light insensitive layer from said light sensitive layer to prevent the formation of a permanent color veil in said light insensitive layer.

5. A photographic material comprising a light sensitive silver halide emulsion layer containing a dyestuif adapted to bereactedwithl a silver image formed in said layer to destroy the dyestuif where silver is present, and a light insensitive layer adjacent said light sensitive layer containing a proportion of exposed silver halide adapted to be converted into metallic silver upon development to assist in the destruction of any dyestuif diifusinginto said light insensitive layer, whereby the formation of a color veil in said light insensitive layer is prevented.

6. A photographic material comprising a light sensitive silver halide emulsion layer containing a dyestuif adapted to be reacted with' a silver image formed in said layer to destroy the dyestuif where silver is present, and a light'insensitive layer adjacent thereto containing a proportion of colloidal silver for assisting in the destruction of any dyestuflf diffusing into said light Port.

. PAUL KNOCHE. 

